Ship&#39;s davit



H. G. TAYLOR SHIPS DAVIT Filed Jan. 5, 1951 INVENTOR HUMPHREY GEORGETAYLOR ATTORNEY Patented Dec. 30, 1952 SHIPS DAVIT Humphrey G. Taylor,Lower Penn, near Wolverhampton, England Application January 3, 1951,Serial No. 204,138 In Great Britain January 9, 1950 4 Claims.

so as to overhang the bow and stern of the susv pended boat. would besuitable for withstanding the stresses imposed on the arm but when thearm is built up, as it usually is, from flat plates or strips suitablyshaped and bent and then welded together it has the disadvantage thatthe welds occur at \points of high stress concentration. The presentinvention provides a rectangular box-section construction in which thisdisadvantage is largely avoided.

A davit arm according to the present invention comprises inner and outermembers of boxsection for at least the greater part of their length, theinner and outer members being interconnected by one or more web or sideplates of suitable thickness to give lateral rigidity, the said plate orplates being welded electrically or otherwise to the box-sectionmembers.

The invention further comprises a davit arm in which the box-sectioninner and outer members are extruded in aluminium alloy and the web orside plates are of similar material. Alloys which are suitable for thisconstruction and are resistant to sea-water corrosion, are BritishStandards Institution Specifications BS/STA7., A. W. 4., A. W. 5., A. W.6., A. W. 7., A. W. 9., and A. W. 10.

The invention will now be described with reference to the embodimentshown, by way of example, in the accompanying drawings; wherein- Fig. 1is a side elevation of a ships davit with the ships boat suspendedtherefrom, the inboard position being shown in full lines and theoutboard position in chain lines.

Fig. 2 is an elevation of the davit as seen from inboard.

Fig. 3 is a section taken on the line 3, 3 of Fig. 1 and drawn to alarger scale for the sake of clearness.

Referring to the drawings, each davit is of the kind comprising a davitarm I which is approximately crescent-shaped in the vertical plane inwhich it is swung or luifed about the pivot pin 2 connecting its lowerend to a deck fitting or A simple rectangular box-section frame 3, suchswinging movements being effected by screw gear 4 operated through bevelgearing 5 from a crank handle 6 at one end and connected at its otherend to a bracket I on the davit arm I. The ships boat 8 is suspendedfrom the free ends of the davit arms I by the usual wire falls 9 andfall blocks ID.

The crescent shaped davit arm I is of fabricated construction, beingbuilt up from inner and outer members I I respectively which are oftubular box section, extruded in aluminium alloy, and web or side platesI of suitable thickness to give lateral rigidity, said web or sideplates I being edge welded, electrically or otherwise, to the tubularbox section members I I The tubular box section members I I are formedor bent to the required shapes and the web or side plates I, which areflat, are edge shaped or profiled to suit, that is to say so that theirinner and outer edges will conform to the confronting faces of the boxsection members I", I to which they are Welded. In this connection theWeb or side plates I are welded to the box section inner and outermembers I I so that they lie flush with, or almost flush with, the sidefaces of said box section members, and to facilitate the correct location of said plates I the box section members I", I may be formed atappropriate positions on their confronting faces with longitudinal ribsor other abutments (not shown) against which the plates I can bepositioned for welding.

The complete section of the davit arm I comprises, as shown in Fig. 3,the two box sections of the inner and outer members I, I and anintermediate box section defined by the confronting faces of thesemembers and the interconnecting plates I which are edge welded theretoin laterally spaced relation.

At the lower end of the davit arm I the box section members I I havetheir end portions bifurcated and spaced or separated laterally toafford two widely separated bearings I3 for pivotal engagement with thepivot pin 2, the gaps between the separated parts of the lower endportions of said members I", I being filled in by appropriately shapedgusset plates welded in position.

If the arm is to have an end portion which is tapered in the lateralplane perpendicular to the web or side plates, this can be attained bycutting away the confronting end portions of the inner and outerbox-section members to remove the requisite amount of material to allowthe cut edges to be brought together and welded.

When the davit arm is manufactured from aluminium alloy, steel or otherbrackets may be riveted to it for connection to the deck fitting orframe, luffing gear and the boat suspending and lowering gear.

In the construction employing, for the davit arm, inner and outerbox-section members interconnected by one or more web or side plateswhich are edge welded to the confronting faces of saidmembers, the linesof weld are nearer to the vertical axis of the arm than would be thecase if the arm were of simple rectangular boxsection fabricated frominner, outer and side wall plates; consequently the welds are subjectedto comparatively less stress.

When the davit arm accordin to this invention is made of aluminium alloythere is a considerable reduction in weight as compared with a steeldavit of similar strength.

Having fully described my invention, what I claim and desire to secureby Letters Patent is:

l. A davit arm construction curved throughout a substantial portion ofits length and of varying depth over a substantial portion of its lengthand being of a minimum depth at its ends, said davit arm being ofsubstantially constant width, pivot means at one end thereof with theaxis of said pivot being transverse to the depth of said arm, each edgeof said arm including a tubular member extending fromend to end of saidarm, said arm including at least one web extending between said tubesand secured thereto throughout substantially the entire length of saidarm.

2. A light weight davit arm comprising a pair of tubular membersarranged in spaced relation and lying in substantiall the same plane,said tubular members being spaced from each other a substantial distanceintermediate their ends forming a beam of varying depth, at least onesubstantially continuous web extending between and contacting saidtubular members throughout substantially the length of said tubularmembers and secured to said tubular members substantially throughout thelength thereof whereby resistance to buckling of the tubular members isincreased.

A S o li W ight davit arm comprising a pair of tubular box sectionmembers arranged in spaced relation in substantially the same plane,said tubular box section members bein spaced from each other a greaterdistance intermediate their ends than at their ends, the distancebetween the remote edges of the tubular box members determining thedepth of the arm, a pair of web plates each positioned on one of theopposite sides of said tubular box members and secured throughout itslength to said tubular box members, said web plates bein continuous fromone end to the other end and shaped to correspond with the shape of thetubular box members.

4. A strong light weight davit arm comprising a pair of tubular boxsection members arranged in spaced side by side relation with the remoteedges of the members determining the depth of the arm, a first web platepositioned between the members adjacent the side edges of the membersand within the sides of said tubular box section members and securedthereto throughout the length of said first web plate, a second webplatepositioned between the members adjacent the other side edges of themembers and secured to said members throughout the length of the secondweb plate, said first and second web plates being continuous from oneend to the other and approximately the length of said members.

HUMPHREY G, TAYLOR.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,538,783 Dingertz May 19, 19252,048,561 Neveling July 21, 1936 2,304,718 Swart Dec. 8, 1942 2,460,982Gilpin Feb. 8, 1949 FOREIGN PATENTS Number Country Date 593,307 GreatBritain Oct. 14, 1947

